Fox McCloud

I had a few questions about the 1991 300D 2.5 Turbo.

Here of late my family has been considering purchasing a '91 300D 2.5 Turbo...I had a few questions about it.

I have heard in general that is is a really good car, and that, in general, I will not have to worry about much maintenance.....except for failure of the AC eventually.

I am considering using home-brew BioDiesel in this vehicle, and was wondering if it will need any modifications? I know BioDiesel is extremely clean, and can dissolve certain rubber seals....and I was wondering whether or not this particular car would need those items replaced or not in order to safely run BioDiesel....

H-townbenzoboy

The W124s are good cars. Very reliable. Yes, the AC seems to be a weak point of most MBs from that era. You can use biodiesel, but I know people sometimes say home-brewed biodiesel when what they really mean is SVO or WVO. Are you sure you're going to run home made biodiesel then? If so, be very cautious, if the viscosity is not good enough, you'll get problems with the fuel system and possibly the IP. In order to effectively run biodiesel, you'll need to change all of your fuel lines out to viton, and change your spin on and inline fuel filters before you start running biodiesel. Biodiesel has excellent cleaning properties, and will clean crud out of your fuel tank. You'll have to replace the inline fuel filter often, and perhaps change the tank screen/strainer if it gets too clogged up with crud. After a while, the tank and fuel system will be fully cleaned, and you won't have to change out your filters so quickly. How long that'll take, I don't know, that depends on how dirty your fuel tank is.

-Joe

Fox McCloud

When I say home-brewed biodiesel, I mean REAL biodiesel.....Waste Vegetable oil that has been filtered, properly heated, mixed with methanol, and lye....also washed, etc.

At first I was considering a straight vegetable oil system until I read all that you had to do to modify the car.

I have read that all one must do is replace all the seals with viton, and change out the fuel filter until the car is completely clean...Would you happen to have any further information on this whole process? Thanks.

H-townbenzoboy

I would replace all the rubber components in the fuel system with viton. Go to the dealer, and buy all new rubber components and lines for the fuel system. They'll stand up to the biodiesel better than what's currently on there if you have all original lines.

ryanrod

I think this guy is referring to the 80's diesels, the 1990's and on have lines that take biodiesel. The older 80's ones would deteriorate, not yours tho. Im speaking from what I have read in other posts...

H-townbenzoboy

Lines after 1996 or so are fine, but this W124 in particular is a 1991, which is still prone to accelerated fuel hose deteriation while using biodiesel like the older models do.

And just for the record, I've recently found out you don't need the expensive viton hose. Regular brand new fuel line does just fine with biodiesel. The reason you see so many fuel line failures using biodiesel has to do with the age of the hose, not the material it's made from.